U.S. patent number 10,515,239 [Application Number 16/098,871] was granted by the patent office on 2019-12-24 for transmission device and transmission system.
This patent grant is currently assigned to eNFC Inc.. The grantee listed for this patent is eNFC Inc.. Invention is credited to Takanori Washiro.
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United States Patent |
10,515,239 |
Washiro |
December 24, 2019 |
Transmission device and transmission system
Abstract
A transmission device includes a magnetic field antenna and an
electric field antenna connected electrically to the magnetic field
antenna. When the magnetic field antenna is at a position allowing
reception of a magnetic field signal transmitted by another
magnetic field antenna included in a magnetic field transmission
device, the transmission device becomes capable of transmitting an
electric field signal generated on the basis of the magnetic field
signal. The electric field antenna is grounded by being connected
electrically to a ground to which the magnetic field transmission
device is connected.
Inventors: |
Washiro; Takanori (Tokyo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
eNFC Inc. |
Minato-ku, Tokyo |
N/A |
JP |
|
|
Assignee: |
eNFC Inc. (Minato-ku, Tokyo,
JP)
|
Family
ID: |
57756196 |
Appl.
No.: |
16/098,871 |
Filed: |
December 13, 2016 |
PCT
Filed: |
December 13, 2016 |
PCT No.: |
PCT/JP2016/087073 |
371(c)(1),(2),(4) Date: |
November 05, 2018 |
PCT
Pub. No.: |
WO2017/199458 |
PCT
Pub. Date: |
November 23, 2017 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
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US 20190188424 A1 |
Jun 20, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
May 17, 2016 [JP] |
|
|
2016-098819 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B
13/00 (20130101); H04B 5/02 (20130101); G06K
7/087 (20130101); G06K 7/10 (20130101); G06K
7/10316 (20130101); H04B 1/59 (20130101); H04B
1/3877 (20130101) |
Current International
Class: |
G06K
7/08 (20060101); G06K 7/10 (20060101); H04B
1/3877 (20150101); H04B 1/59 (20060101); H04B
5/02 (20060101); H04B 13/00 (20060101) |
Field of
Search: |
;235/492,375,487 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2003216911 |
|
Jul 2003 |
|
JP |
|
2006324774 |
|
Nov 2006 |
|
JP |
|
2009081771 |
|
Apr 2009 |
|
JP |
|
2013148954 |
|
Aug 2013 |
|
JP |
|
2014030317 |
|
Feb 2014 |
|
WO |
|
Other References
Aug. 30, 2016, Notification of Reasons for Refusal issued by the
Japan Patent Office in the corresponding Japanese Patent
Application No. 2016-098819. cited by applicant .
Jan. 24, 2017, International Search Report issued in the
International Patent Application No. PCT/JP2016/087073. cited by
applicant .
Nov. 20, 2018, International Preliminary Report on Patentability
issued in the International Patent Application No.
PCT/JP2016/087073. cited by applicant .
Apr. 11, 2019, the partial supplementary European search report
issued by the European Patent Office in the rresponding European
Patent Application No. 16902476.7. cited by applicant .
Jul. 16, 2019, the Extended European Search Report issued by the
European Patent Office in the corresponding European Patent
Application No. 16902476.7. cited by applicant.
|
Primary Examiner: Labaze; Edwyn
Attorney, Agent or Firm: Kenja IP Law PC
Claims
The invention claimed is:
1. A transmission device comprising: a magnetic field antenna; and
an electric field antenna connected electrically to the magnetic
field antenna; wherein when the magnetic field antenna is at a
position allowing reception of a magnetic field signal transmitted
by another magnetic field antenna included in a magnetic field
transmission device, the transmission device becomes capable of
transmitting an electric field signal generated on the basis of the
magnetic field signal; and wherein the electric field antenna is
grounded by being connected electrically to a terminal line having
an electrical length of ((2n+1).times.90.+-.45).degree., where n is
an integer of at least 0, relative to the electric field
signal.
2. The transmission device of claim 1, wherein the transmission
device is configured to be attachable to and detachable from the
magnetic field transmission device.
3. A transmission system comprising: an electric field antenna
connected electrically to a magnetic field antenna; a magnetic
field transmission device comprising a communication circuit,
configured to control a signal to be transmitted, and another
magnetic field antenna connected electrically to the communication
circuit; and an electric field communication device comprising a
transceiver unit configured to transmit and receive an electrical
signal and a coupling electrode connected to the transceiver unit
and configured to couple to a transmission medium; wherein the
electric field communication device performs electric field
communication through the transmission medium when the transmission
medium is coupled to the electric field antenna and the coupling
electrode while the magnetic field antenna is at a position
allowing reception of a magnetic field signal transmitted by the
another magnetic field antenna; wherein the electric field antenna
is configured to be attachable to and detachable from the magnetic
field transmission device; wherein the electric field communication
device further comprises another coupling electrode; and wherein a
length from the coupling electrode to an end of the transmission
medium in a longitudinal direction is an electrical length in a
range of (2n.times.90.+-.45).degree., where n is an integer of at
least 0, relative to the electrical signal, a length from the
another coupling electrode to another end of the transmission
medium in the longitudinal direction is an electrical length in a
range of ((2n+1).times.90.+-.45).degree. relative to the electrical
signal, and the electric field communication device performs the
electric field communication by the electric field antenna coupling
to a region of the transmission medium where the electrical length
is in the range of (2n.times.90.+-.45).degree. relative to the
electrical signal.
4. The transmission system of claim 3, wherein the electric field
communication device further comprises: an insertion portion
allowing insertion of a magnetic field communication device
comprising a magnetic field antenna; and a magnetic field antenna
configured to receive a magnetic field signal transmitted by the
magnetic field antenna of the magnetic field communication device.
Description
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority to and the benefit of
Japanese Patent Application No. 2016-098819 filed May 17, 2016, the
entire contents of which are incorporated herein by reference.
TECHNICAL FIELD
The present disclosure relates to a transmission device and a
transmission system that can achieve both magnetic field
communication using magnetic field signals and electric field
communication using electric field signals.
BACKGROUND
Contactless systems (magnetic field communication systems) that use
a contactless integrated circuit (IC) card are known. Such
contactless systems are, for example, used as electronic tickets
and electronic money. In a contactless communication system, an
antenna included in the contactless IC card receives a magnetic
field signal transmitted by a magnetic field antenna in a
reader/writer (R/W) device and transmits predetermined information
in response as a magnetic field signal to the R/W device.
Communication is thus established between the contactless IC card
and the R/W device. Patent literature (PTL) 1, for example,
discloses an example of a contactless communication system.
A transmission system that uses a dielectric as a transmission
medium to transmit a high-frequency signal or high-frequency power
is also known. In particular, such a transmission system is
referred to as a human body communication system, for example, when
the dielectric is a human body. In the human body communication
system, communication with a transmission device is established
when the human body touches an electrode of the transmission
device, whereas communication with the transmission device is not
established when the human body is not touching an electrode of the
transmission device. PTL 2 and PTL 3, for example, disclose
examples of a human body communication system.
CITATION LIST
Patent Literature
PTL 1: JP2003216911A
PTL 2: JP2006324774A
PTL 3: JP2013148954A
SUMMARY
Technical Problem
Currently, transmission systems can also be used for
authentication, billing, or the like carried out using a
contactless communication system. Creating new infrastructure for
the transmission system, however, presents a major cost.
Furthermore, ceasing to use an existing contactless communication
system yields an economic loss with respect to the cost for
constructing the existing contactless communication system.
Moreover, if some users wished to use a contactless communication
system whereas other users wished to use a transmission system such
as a human body communication system, it would significantly
increase costs to create two independent systems to satisfy both
groups of customers.
In light of these considerations, the present disclosure aims to
provide a transmission device and a transmission system capable of
implementing both magnetic field communication and electric field
communication.
Solution to Problem
To solve the above problem, a transmission device according to a
first aspect includes:
a magnetic field antenna; and
an electric field antenna connected electrically to the magnetic
field antenna;
such that when the magnetic field antenna is at a position allowing
reception of a magnetic field signal transmitted by another
magnetic field antenna included in a magnetic field transmission
device, the transmission device becomes capable of transmitting an
electric field signal generated on the basis of the magnetic field
signal; and
such that the electric field antenna is grounded by being connected
electrically to a ground to which the magnetic field transmission
device is connected.
A transmission device according to a second aspect includes:
a magnetic field antenna;
an electric field antenna connected electrically to the magnetic
field antenna; and
an electrode;
such that when the magnetic field antenna is at a position allowing
reception of a magnetic field signal transmitted by another
magnetic field antenna included in a magnetic field transmission
device, the transmission device becomes capable of transmitting an
electric field signal generated on the basis of the magnetic field
signal; and
such that the electric field antenna is grounded by the electrode
capacitively coupling to a ground to which the magnetic field
transmission device is connected.
A transmission device according to a third aspect includes:
a magnetic field antenna; and
an electric field antenna connected electrically to the magnetic
field antenna;
such that when the magnetic field antenna is at a position allowing
reception of a magnetic field signal transmitted by another
magnetic field antenna included in a magnetic field transmission
device, the transmission device becomes capable of transmitting an
electric field signal generated on the basis of the magnetic field
signal; and
such that the electric field antenna is grounded by being connected
electrically to a terminal line having an electrical length of
((2n+1).times.90.+-.45).degree., where n is an integer of at least
0, relative to the electric field signal.
In a transmission device according to a fourth aspect, the
transmission device is configured to be attachable to and
detachable from the magnetic field transmission device.
A transmission system according to a fifth aspect includes:
an electric field antenna connected electrically to a magnetic
field antenna;
a magnetic field transmission device including a communication
circuit, configured to control a signal to be transmitted, and
another magnetic field antenna connected electrically to the
communication circuit; and
an electric field communication device including a transceiver unit
configured to transmit and receive an electrical signal and a
coupling electrode connected to the transceiver unit and configured
to couple to a transmission medium;
such that the electric field communication device performs electric
field communication through the transmission medium when the
transmission medium is coupled to the electric field antenna and
the coupling electrode while the magnetic field antenna is at a
position allowing reception of a magnetic field signal transmitted
by the another magnetic field antenna; and
such that the electric field antenna is configured to be attachable
to and detachable from the magnetic field transmission device.
In a transmission system according to a sixth aspect, the electric
field communication device further includes:
an insertion portion allowing insertion of a magnetic field
communication device including a magnetic field antenna; and
a magnetic field antenna configured to receive a magnetic field
signal transmitted by the magnetic field antenna of the magnetic
field communication device.
In a transmission system according to a seventh aspect, the
electric field communication device further includes another
coupling electrode; and
a length from the coupling electrode to an end of the transmission
medium in a longitudinal direction is an electrical length in a
range of (2n.times.90.+-.45).degree., where n is an integer of at
least 0, relative to the electrical signal, a length from the
another coupling electrode to another end of the transmission
medium in the longitudinal direction is an electrical length in a
range of ((2n+1).times.90.+-.45).degree. relative to the electrical
signal, and the electric field communication device performs the
electric field communication by the electric field antenna coupling
to a region of the transmission medium where the electrical length
is in the range of (2n.times.90.+-.45).degree. relative to the
electrical signal.
Other aims, features, and advantages of the present disclosure will
become clear in the detailed description below, which is based on
embodiments of the present disclosure and the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a functional block diagram illustrating the schematic
configuration of a transmission device according to a first
embodiment of the present disclosure;
FIG. 2 illustrates an example of an electric field communication
device;
FIG. 3 schematically illustrates operation of the electric field
communication device in FIG. 2;
FIG. 4 is a functional block diagram illustrating the schematic
configuration of a transmission device according to a second
embodiment of the present disclosure;
FIG. 5 is a functional block diagram illustrating the schematic
configuration of a transmission device according to a third
embodiment of the present disclosure;
FIG. 6 is a functional block diagram illustrating the schematic
configuration of a transmission device according to a fourth
embodiment of the present disclosure;
FIG. 7 is a functional block diagram illustrating the schematic
configuration of a transmission system according to a fifth
embodiment of the present disclosure;
FIG. 8 is a functional block diagram illustrating the schematic
configuration of a transmission system according to a sixth
embodiment of the present disclosure;
FIG. 9 schematically illustrates the state in which a card holder
is coupled to a dielectric;
FIG. 10 schematically illustrates an example of a coupled state
allowing electric field communication to be established between a
card holder and a transmission device;
FIG. 11 schematically illustrates an example of a coupled state in
which electric field communication is not established between a
card holder and a transmission device; and
FIG. 12 schematically illustrates an example of a transmission
system configured by coupling a card holder to a human body.
DETAILED DESCRIPTION
Embodiments of the present disclosure are described below in detail
with reference to the drawings.
First Embodiment
FIG. 1 is a functional block diagram illustrating the schematic
configuration of a transmission device 100 according to the first
embodiment of the present disclosure. The transmission device 100
includes a communication circuit 110, a magnetic field antenna 120,
a matching circuit (resonant circuit) 130, and a signal electrode
140. The transmission device 100 can use the magnetic field antenna
120 to communicate via magnetic field signals (magnetic field
communication) with a magnetic field communication device
constituted, for example, by a contactless IC card or the like. The
transmission device 100 can also use the signal electrode 140 to
communicate via electric field signals (electric field
communication) with an electric field communication device coupled
electrically through a transmission medium in contact with the
signal electrode 140. The signal electrode 140 functions as a
portion of an electric field antenna.
First, magnetic field communication by the transmission device 100
is described together with the functional blocks of the
transmission device 100.
The communication circuit 110 controls the signals output from the
magnetic field antenna 120 and the electric field antenna in the
transmission device 100. During communication via magnetic field
signals, the communication circuit 110 transmits a control signal
to the magnetic field antenna 120 for causing the magnetic field
antenna 120 to transmit a magnetic field signal of a predetermined
frequency. The communication circuit 110 also performs information
processing on the magnetic field signals received by the magnetic
field antenna 120 from a magnetic field communication device such
as a contactless IC card. The communication circuit 110 is
connected to ground.
The magnetic field antenna 120 is connected to the communication
circuit 110 and transmits a magnetic field signal of a
predetermined frequency in accordance with the control signal from
the communication circuit 110. The magnetic field antenna 120 is,
for example, formed by a loop antenna. The magnetic field signal
transmitted by the magnetic field antenna 120 is received by a
magnetic field communication device (not illustrated). The magnetic
field communication device includes an antenna capable of
communicating with the transmission device 100 via magnetic field
signals and an IC chip that stores predetermined information and
controls the entire communication device. After receiving a
magnetic field signal, the magnetic field communication device
converts information inside the IC chip to a signal and transmits
the signal from the antenna. The magnetic field antenna 120
receives magnetic field signals from the magnetic field
communication device.
When the magnetic field communication device, such as a contactless
IC card, is placed within a range capable of receiving magnetic
field signals transmitted by the magnetic field antenna 120,
magnetic field communication via magnetic field signals is
established between the transmission device 100 and the magnetic
field communication device. The communication circuit 110 and the
magnetic field antenna 120 thus function as the magnetic field
transmission device (R/W device) in a known magnetic field
communication system (contactless communication system).
Next, electric field communication by the transmission device 100
is described.
The matching circuit 130 is connected to the communication circuit
110. The matching circuit 130 is a circuit for matching the
impedance of the communication circuit 110 and the impedance of the
electric field communication device. The matching circuit 130 can,
for example, be constituted by a known LC circuit combining a
capacitor, an inductor, and the like. In the present embodiment,
one terminal of the matching circuit 130 is connected to
ground.
The signal electrode 140 is a coupling electrode that, during
electric field communication, couples with a transmission medium
constituted by a conductor, such as metal, or a dielectric. The
signal electrode 140 is, for example, formed by a metal plate.
FIG. 2 illustrates an example of an electric field communication
device capable of electric field communication with the
transmission device 100. The electric field communication device
150 includes two input/output (I/O) terminals 152a and 152b and a
transceiver 151 connected to the two I/O terminals 152a and 152b.
During communication with the transmission device 100, the
transceiver 151 transmits and receives high-frequency signals (or
high-frequency power) between 10 kHz and 10 GHz, for example. One
of the I/O terminals of the electric field communication device
150, i.e. the I/O terminal 152a, is connected to ground or to a
terminal line 170 that functions as a virtual ground. Details on
the terminal line 170 are provided below. When the other I/O
terminal 152b of the electric field communication device 150 is
coupled electrically to the signal electrode 140 through a
transmission medium, electric field communication is established
between the transmission device 100 and the electric field
communication device 150. The matching circuit 130 and the signal
electrode 140 thus function as an electric field antenna.
As described above, the magnetic field antenna 120 and the electric
field antenna (matching circuit 130 and signal electrode 140) are
connected to one communication circuit 110 in the transmission
device 100 according to the present embodiment. The transmission
device 100 can therefore transmit signals with the same content
(data) simultaneously from both the magnetic field antenna 120 and
the electric field antenna. Consequently, the user can freely
choose between magnetic field communication and electric field
communication.
Furthermore, the transmission device 100 is configured by providing
the communication circuit 110 and the magnetic field antenna 120,
which function as the magnetic field transmission device in a known
magnetic field communication system, with the matching circuit 130
and the signal electrode 140. The transmission device 100 can
therefore be configured by constructing a transmission system based
on electric field signals on top of an existing magnetic field
communication system. In other words, the transmission device 100
is configured by using an existing magnetic field communication
system and providing an electric field antenna for electric field
communication. Consequently, the transmission device 100 allows a
reduction in the cost for producing devices as compared to when
newly constructing a device with both the functions of known
magnetic field communication (contactless communication) and
electric field communication. The transmission device 100 can also
be used without the need to discard an existing magnetic field
communication system.
The terminal line functioning as a virtual ground is now described
with reference again to FIG. 2. As an example, the electric field
communication device 150, a transmission medium 160, and the
terminal line 170 are depicted in FIG. 2.
The electric field communication device 150 includes the two I/O
terminals 152a and 152b and the transceiver 151. One of the I/O
terminals, i.e. the I/O terminal 152b, is a terminal for
electrically coupling to the transmission medium 160. The other I/O
terminal 152a is coupled electrically to the terminal line 170
formed by a conductor, such as metal, or a dielectric. As an
example, the transceiver 151 is described here as transmitting
high-frequency signals.
When the transceiver 151 transmits a high-frequency signal by
electric field communication with the transmission device 100,
current flows to the terminal line 170 from the I/O terminal 152a
of the transceiver 151 coupled to the terminal line 170. At the
same time, current of the same magnitude as the current flowing to
the terminal line 170 flows in the opposite direction from the I/O
terminal 152b to the transmission medium 160. In this way, the
transceiver 151 sends a high frequency signal to the transmission
medium.
The terminal line 170 has an electrical length of 90.degree.. An
electrical length of 90.degree. means that the length of the line
from the end 170a connected to the I/O terminal 152a to the other
end 170b is one quarter of the wavelength of the high frequency
signal to be transmitted. In other words, the phase of the high
frequency signal to be transmitted advances 90.degree. over the
length from the end 170a connected to the I/O terminal 152a to the
other end 170b.
Consequently, the current that flows to the terminal line 170 side
from the end 170a connected to the input/output terminal 152a is
subsequently reflected at the other end 170b of the terminal line
170 and returns to the end 170a connected to the input/output
terminal 152a, thereby traversing a distance of half a wavelength.
The phase thus advances 180.degree..
At this time, as illustrated in FIG. 2, the transceiver 151 inputs
a high frequency signal to the terminal line 170, which has an
electrical length of 90.degree., i.e. one quarter of the wavelength
of the high frequency signal to be transmitted, and the end 170b of
which is open. Consequently, a standing wave is generated in the
terminal line 170, with maximum voltage amplitude and zero current
amplitude at the end 170b and zero voltage amplitude and maximum
current amplitude at the end 170a, and current flows to the end
170a. In other words, when the terminal line 170 has an electrical
length of 90.degree., the voltage amplitude at the end 170a is
zero, but current flows. Hence, as illustrated schematically in
FIG. 3, the end 170a behaves as though it were virtually short
circuited to ground. The I/O terminal 152a connected to the
terminal line 170 can thus be considered a short-circuit terminal
that is virtually connected to ground.
As illustrated in FIG. 2, the current that flows into the I/O
terminal 152a is maximized when the electrical length of the
terminal line 170 is 90.degree., i.e. when the signal input from
the end 170a of the terminal line 170 connected to the I/O terminal
152a of the transceiver 151 is reflected at the other end 170b and
returns so that the phase of the reflected wave is 180.degree..
Consequently, electric field communication is most efficient when
the electrical length of the terminal line 170 is 90.degree..
During electric field communication, however, a certain advantage
in high frequency transmission is still obtained by the electrical
length of the terminal line 170 being within a range of
.+-.45.degree. C. of 90.degree. C., i.e. with the phase of the
reflected wave being in a range greater than 90.degree. C. and
smaller than 270.degree. C. It thus suffices for the terminal line
170 to have an electrical length of substantially 90.degree., which
includes a range of .+-.45.degree. C. from 90.degree. C. The
terminal line 170 may have an electrical length of
((2n+1).times.90.+-.45).degree., where n is an integer of at least
0. When the terminal line 170 has an electrical length of
((2n+1).times.90.+-.45).degree., the terminal line 170 functions as
a virtual ground by the same principle as described with reference
to FIG. 2.
Second Embodiment
FIG. 4 is a functional block diagram illustrating the schematic
configuration of a transmission device 200 according to the second
embodiment of the present disclosure. The transmission device 200
includes a communication circuit 210, a first magnetic field
antenna 220, a matching circuit (resonant circuit) 230, a signal
electrode 240, and a second magnetic field antenna 250. The
transmission device 200 according to the present embodiment can
perform magnetic field communication with a magnetic field
communication device and electric field communication with an
electric field communication device, like the transmission device
100 according to the first embodiment. A description of points
similar to the transmission device 100 according to the first
embodiment is omitted below as appropriate to focus mainly on the
differences.
The transmission device 200 according to the present embodiment is
substantially configured by two transmission devices. One of the
transmission devices (first transmission device) is a magnetic
field transmission device that includes the communication circuit
210 and the first magnetic field antenna 220. The first
transmission device is, for example, an existing magnetic field
transmission device. The other transmission device (second
transmission device) includes the matching circuit 230, the signal
electrode 240, and the second magnetic field antenna 250. The
transmission device 200 according to the second embodiment is
configured by combining the first transmission device and the
second transmission device.
The communication circuit 210 according to the present embodiment
corresponds to the communication circuit 110 of the first
embodiment and controls signals output by the first magnetic field
antenna 220. The communication circuit 210 is connected to ground.
The first magnetic field antenna 220 corresponds to the magnetic
field antenna 120 in the first embodiment and transmits a magnetic
field signal of a predetermined frequency in accordance with a
control signal from the communication circuit 210. The
communication circuit 210 and the first magnetic field antenna 220
are, for example, known equipment (a magnetic field transmission
device) for achieving magnetic field communication.
When a magnetic field communication device (not illustrated) is
placed within a range capable of receiving magnetic field signals
transmitted by the first magnetic field antenna 220, magnetic field
communication is established between the transmission device 200
and the magnetic field communication device. In the present
embodiment, the communication circuit 210 and the first magnetic
field antenna 220 function as a magnetic field transmission device
in a known magnetic field communication system.
In the present embodiment, the second magnetic field antenna 250 is
arranged in a position allowing receipt of magnetic field signals
transmitted by the first magnetic field antenna 220. The second
magnetic field antenna 250 is connected to the matching circuit
230. When a magnetic field signal transmitted by the first magnetic
field antenna 220 is received in the second magnetic field antenna
250, a control signal to be provided to the matching circuit 230 is
generated in the second magnetic field antenna 250 on the basis of
the received magnetic field signal. The control signal generated in
the second magnetic field antenna 250 is provided to the matching
circuit 230.
The functions of the matching circuit 230 and the signal electrode
240 in the present embodiment are similar to those of the matching
circuit 130 and the signal electrode 140 in the first embodiment.
The present embodiment differs from the first embodiment in that a
signal from the second magnetic field antenna 250 is provided to
the matching circuit 230.
In the present embodiment as well, electric field communication
between the transmission device 200 and an electric field
communication device is established when the signal electrode 240
is electrically coupled through a transmission medium to the
electric field communication device. In other words, the matching
circuit 230 and the signal electrode 240 function as an electric
field antenna in the present embodiment.
In this way, the transmission device 200 according to the present
embodiment as well can transmit signals with the same content
(data) simultaneously from both the first magnetic field antenna
220 and the electric field antenna. Consequently, the user can
freely choose between magnetic field communication and electric
field communication.
Furthermore, even when the first transmission device that functions
as a magnetic field transmission device is provided as existing
equipment, for example, the transmission device 200 can be
configured by providing the existing first transmission device with
a new second transmission device. The transmission device 200 can
thus be configured by using an existing magnetic field
communication system and providing an electric field antenna for
electric field communication. Consequently, the transmission device
200 allows a reduction in the cost for producing devices as
compared to when newly constructing a device with both the
functions of known magnetic field communication and electric field
communication. The transmission device 200 can also be used without
the need to discard an existing magnetic field communication
system. Furthermore, no wiring work for connecting the
communication circuit 210 and the matching circuit 230 to existing
equipment is required in the present embodiment, making it easier
to provide existing equipment with an electric field antenna. When
the outer case of the first transmission device, which is existing
equipment, is made from grounded metal or the like, then a ground
connection is also easy to make, and the transmission device 200
can be configured by attaching the second transmission device to
the outside of the existing equipment.
Third Embodiment
FIG. 5 is a functional block diagram illustrating the schematic
configuration of a transmission device 300 according to the third
embodiment of the present disclosure. The transmission device 300
includes a communication circuit 310, a first magnetic field
antenna 320, a matching circuit (resonant circuit) 330, a signal
electrode 340, a second magnetic field antenna 350, and a ground
electrode 360.
The transmission device 300 according to the present embodiment is
configured by two independent transmission devices. One of the
independent transmission devices (first transmission device) is a
magnetic field transmission device that includes the communication
circuit 310 and the first magnetic field antenna 320. The first
transmission device is, for example, an existing magnetic field
transmission device. The other independent transmission device
(second transmission device) includes the matching circuit 330, the
signal electrode 340, the second magnetic field antenna 350, and
the ground electrode 360. In other words, the transmission device
300 according to the third embodiment is configured by combining
the first transmission device and the second transmission
device.
The transmission device 300 according to the present embodiment can
perform magnetic field communication with a magnetic field
communication device and electric field communication with an
electric field communication device, like the transmission device
200 according to the second embodiment. A description of points
similar to the transmission device 200 according to the second
embodiment is omitted below as appropriate to focus mainly on the
differences.
The communication circuit 310, the first magnetic field antenna
320, the matching circuit 330, the signal electrode 340, and the
second magnetic field antenna 350 included in the transmission
device 300 correspond respectively to the communication circuit
210, the first magnetic field antenna 220, the matching circuit
230, the signal electrode 240, and the second magnetic field
antenna 250 included in the transmission device 200 according to
the second embodiment. Hence, a detailed description thereof is
omitted. The matching circuit 330 and the signal electrode 340
function as an electric field antenna in the present
embodiment.
In the transmission device 300 according to the present embodiment,
the matching circuit 330 is not connected to ground, unlike the
transmission device 200 according to the second embodiment. The
matching circuit 330 of the transmission device 300 is connected to
the ground electrode 360 formed by a metal plate or the like. The
ground electrode 360 is arranged near the ground to which the
communication circuit 310 is connected. Here, near the ground
refers to a position at which the ground electrode 360 is capable
of capacitive coupling with the metal plate or the like forming the
ground to which the communication circuit 310 is connected. In
other words, the ground electrode 360 is connected to the ground by
capacitive coupling. Consequently, the matching circuit 330
connected to the ground electrode 360 is substantially in a state
of being connected to ground.
Like the transmission device 200 according to the second
embodiment, the transmission device 300 according to the third
embodiment can also transmit signals with the same content (data)
simultaneously from both the first magnetic field antenna 320 and
the electric field antenna (matching circuit 330 and signal
electrode 340). Consequently, the user can freely choose between
magnetic field communication and electric field communication.
Like the transmission device 200 according to the second
embodiment, the transmission device 300 can also be configured by
using an existing magnetic field communication system (first
transmission device) and providing an electric field antenna
(second transmission device) for electric field communication.
Consequently, the transmission device 300 allows a reduction in the
cost for producing devices as compared to when newly constructing a
device with both the functions of known magnetic field
communication and electric field communication. The transmission
device 300 can also be used without the need to discard an existing
magnetic field communication system. Furthermore, no wiring work
for connecting the communication circuit 210 and the matching
circuit 230 to existing equipment is required in the present
embodiment, and the matching circuit 330 need not be connected to
ground. The independent second transmission device can therefore be
used in the present embodiment in combination with the first
transmission device, which is existing equipment. Furthermore, the
second transmission device can easily be attached to and detached
from the first transmission device, since the second transmission
device is configured independently from the first transmission
device.
Fourth Embodiment
FIG. 6 is a functional block diagram illustrating the schematic
configuration of a transmission device 400 according to the fourth
embodiment of the present disclosure. The transmission device 400
according to the fourth embodiment includes a communication circuit
410, a first magnetic field antenna 420, a matching circuit
(resonant circuit) 430, a signal electrode 440, a second magnetic
field antenna 450, and a connection terminal 470. The connection
terminal 470 connects to the terminal line 460 when the
transmission device 400 is used.
The transmission device 400 according to the present embodiment as
well is configured by two independent transmission devices. One of
the independent transmission devices (first transmission device) is
a magnetic field transmission device that includes the
communication circuit 410 and the first magnetic field antenna 420.
The first transmission device is, for example, an existing magnetic
field transmission device. The other independent transmission
device (second transmission device) includes the matching circuit
430, the signal electrode 440, the second magnetic field antenna
450, and the connection terminal 470. The second transmission
device may include a terminal line 460 connected to the connection
terminal 470. The transmission device 400 according to the fourth
embodiment is configured by the second transmission device being
combined with the first transmission device.
The transmission device 400 according to the present embodiment
differs from the transmission device 300 according to the third
embodiment by including the terminal line 460 instead of the ground
electrode 360. The matching circuit 430 and the signal electrode
440 function as an electric field antenna in the present
embodiment.
The terminal line 460 is formed by a conductor, such as metal, or a
dielectric and has an electrical length of nearly 90.degree.. The
terminal line 460 functions as a virtual ground by the
above-described principle during electric field communication by
the transmission device 400. Consequently, the matching circuit 430
is substantially in a state of being connected to ground in the
transmission device 400 according to the present embodiment as
well.
As with the transmission device 300 according to the third
embodiment, the user can thus freely choose between magnetic field
communication and electric field communication with the
transmission device 400 according to the present embodiment. The
transmission device 400 also allows a reduction in the cost for
producing devices as compared to when newly constructing a device
with both the functions of known magnetic field communication and
electric field communication. Furthermore, the independent second
transmission device can be used in the present embodiment in
combination with the first transmission device, which is existing
equipment. The second transmission device can also easily be
attached to and detached from the first transmission device, since
the second transmission device is configured independently from the
first transmission device.
Fifth Embodiment
FIG. 7 is a functional block diagram illustrating the schematic
configuration of a transmission system 500 according to the fifth
embodiment of the present disclosure. In the present embodiment, an
example of communication using a transmission device 510 capable of
selectively performing magnetic field communication and electric
field communication, for example as described above in the first
through fourth embodiments, is described. In the present
embodiment, an example is described of a user using an electronic
ticket 520 to communicate with the transmission device 510, which
is configured as an automatic ticket gate 530. The electronic
ticket 520 in the present embodiment is described as being a
card-type magnetic field communication device (i.e. a contactless
IC card). However, the electronic ticket 520 may have a different
form other than a card.
In the present embodiment, the transmission device 510 includes a
communication circuit 511, a first magnetic field antenna 512, a
matching circuit (resonant circuit) 513, a signal electrode 514,
and a second magnetic field antenna 515. The transmission device
510 according to the present embodiment is configured similarly to
the transmission device 200 according to the second embodiment.
Hence, a detailed description of each functional block in the
transmission device 510 is omitted. Known equipment (a magnetic
field transmission device) for achieving magnetic field
communication may, for example, be used as the communication
circuit 511 and the first magnetic field antenna 512 in the present
embodiment. The matching circuit 513 and the signal electrode 514
function as an electric field antenna in the present
embodiment.
In the transmission device 510 according to the present embodiment,
the signal electrode 514 is arranged on a surface 530a, where
communication takes place, of the automatic ticket gate 530 so that
an electric field signal can be transmitted at the position where a
magnetic field signal is generated by the first magnetic field
antenna 512. A magnetic field signal and an electric field signal
are therefore transmitted from the same position on the surface
530a of the automatic ticket gate 530. In the present disclosure,
this position on the surface 530a is also referred to below as the
"communication position". The automatic ticket gate 530 may include
any display 531 on the surface 530a to indicate the communication
position. This display allows the user to recognize the
communication position in the automatic ticket gate 530 easily.
When a metal plate is present near the magnetic field antenna, as
in the positional relationship between the first magnetic field
antenna 512 and the signal electrode 514 in the present embodiment,
then eddy current might flow in the metal plate, blocking
transmission and reception of signals by the magnetic field
antenna. The transmission device 510 may include any known means
for preventing the occurrence of eddy current. For example, the
signal electrode 514 may be shaped like a comb by forming slits in
the signal electrode 514 to facilitate preventing the occurrence of
eddy current in the transmission device 510.
The electronic ticket 520 includes an IC chip 521, which stores
predetermined information and controls magnetic field communication
processing in the electronic ticket 520, and a magnetic field
antenna 522 capable of communicating with the transmission device
510 by magnetic field signals. To perform magnetic field
communication in the transmission system 500, the user of the
electronic ticket 520 passes the electronic ticket 520 over the
communication position of the automatic ticket gate 530. Magnetic
field communication between the transmission device 510 and the
electronic ticket 520 is thus achieved on the basis of magnetic
field signals transmitted from the first magnetic field antenna
512.
To perform electric field communication in the transmission system
500, the user of the electronic ticket 520 first inserts the
electronic ticket 520 into a dedicated card holder 540, for
example. The card holder 540 has an insertion portion (groove)
configured to allow insertion and removal of the electronic ticket
520. The card holder 540 includes a magnetic field antenna 541, a
matching circuit (resonant circuit) 542, a signal electrode 543,
and a terminal line 544. The configuration of the magnetic field
antenna 541, the matching circuit 542, the signal electrode 543,
and the terminal line 544 in the card holder 540 is equivalent to
that of the second magnetic field antenna 450, the matching circuit
430, the signal electrode 440, and the terminal line 460 of the
transmission device 400 according to the fourth embodiment.
The magnetic field antenna 541 is arranged at a position in the
card holder 540 allowing reception of magnetic field signals from
the magnetic field antenna 522 of the electronic ticket 520 when
the electronic ticket 520 is inserted in the insertion portion. The
magnetic field antenna 541 is connected to the matching circuit
542. When a magnetic field signal transmitted by the magnetic field
antenna 522 of the electronic ticket 520 is received in the
magnetic field antenna 541 of the card holder 540, a control signal
to be provided to the matching circuit 542 is generated in the
magnetic field antenna 541 on the basis of the received magnetic
field signal.
The functions of the matching circuit 542 and the signal electrode
543 are similar to those of the matching circuit 130 and the signal
electrode 140 in the first embodiment, for example. In the present
embodiment, the matching circuit 542 is connected to the terminal
line 544. The terminal line 544 is formed by a conductor, such as
metal, or a dielectric and has an electrical length of nearly
90.degree.. The terminal line 544 functions as a virtual ground by
the above-described principle during electric field communication
in the transmission system 500.
The card holder 540 includes an attachment portion, such as a belt,
allowing the user to attach the card holder 540 to the wrist, arm,
or the like. The user attaches the card holder 540 by, for example,
wrapping the attachment portion around the wrist or the arm. In the
present embodiment, the user is described below as wrapping the
attachment portion around the wrist. The signal electrode 543 is
arranged in the card holder 540 at a position that comes in contact
with the user (human body) when the user has the card holder 540
wrapped around the wrist. In other words, the signal electrode 543
is in a state of being electrically coupled to the user when the
user has the card holder 540 wrapped around the wrist.
To achieve electric field communication in the transmission system
500, the user touches a portion of the body, such as a finger, to
the communication position of the transmission device 510 while
having the card holder 540, with the electronic ticket 520 inserted
therein, wrapped around the wrist. The section of the human body,
which is a dielectric, between the finger or the like that is in
contact with the communication position and the location in contact
with the signal electrode 543 functions at this time as a
transmission medium. Through the human body that is coupled to the
signal electrode 514 directly or by capacitive coupling, an
electric field signal is transmitted to the card holder 540 at the
signal electrode 543 coupled to the human body directly or by
capacitive coupling. Electric field communication is thus achieved
through the human body, which functions as a transmission medium,
between the transmission device 510 and the card holder 540 with
the electronic ticket 520 inserted therein.
In this way, the transmission system 500 according to the present
embodiment allows the user to selectively communicate either by
magnetic field communication or electric field communication. The
user can easily select between magnetic field communication and
electric field communication by inserting the electronic ticket 520
in the card holder 540. Furthermore, the user can use the
electronic ticket 520 capable of magnetic field communication to
perform electric field communication in the transmission system 500
by inserting the electronic ticket 520 in the card holder 540. In
the case of the magnetic field communication system being an
existing system, the transmission system 500 can thus achieve
electric field communication using such existing assets.
Sixth Embodiment
FIG. 8 is a functional block diagram illustrating the schematic
configuration of a transmission system 600 according to the sixth
embodiment of the present disclosure. As in the transmission system
500 according to the fifth embodiment, the user can also
selectively perform magnetic field communication and electric field
communication in the transmission system 600 according to the
present embodiment.
In the present embodiment, as in the case described in the fifth
embodiment, an example is described of the user using an electronic
ticket 620 to communicate with a transmission device 610, which is
configured as an automatic ticket gate. In the present embodiment
as well, the electronic ticket 620 is described as being a
card-type magnetic field communication device.
The transmission device 610 according to the present embodiment is
configured by two independent transmission devices, like the
transmission device 300 according to the third embodiment, for
example. One of the independent transmission devices (first
transmission device 630) is, for example, an existing automatic
ticket gate capable of magnetic field communication. The other
independent transmission device (second transmission device 650) is
configured to include an electric field antenna attachable to and
detachable from the first transmission device 630.
The first transmission device 630 includes a communication circuit
631 and a first magnetic field antenna 632. The functions of the
communication circuit 631 and the first magnetic field antenna 632
are similar to those of the communication circuit 310 and the first
magnetic field antenna 320 in the third embodiment, for example.
Hence, a detailed description thereof is omitted. In the present
embodiment, the communication circuit 631 and the first magnetic
field antenna 632 are, for example, known equipment (a magnetic
field transmission device) for achieving magnetic field
communication.
The second transmission device 650 includes a matching circuit
(resonant circuit) 651, a signal electrode 652, a second magnetic
field antenna 653, and a ground electrode 654. The functions of the
matching circuit 651, the signal electrode 652, the second magnetic
field antenna 653, and the ground electrode 654 are similar to
those of the matching circuit 330, the signal electrode 340, the
second magnetic field antenna 350, and the ground electrode 360 in
the third embodiment, for example. In other words, the second
magnetic field antenna 653 is arranged at a position allowing
reception of magnetic field signals transmitted by the first
magnetic field antenna 632 of the first transmission device 630
when the second transmission device 650 has been mounted on the
first transmission device 630. The matching circuit 651 and the
signal electrode 652 function as an electric field antenna in the
present embodiment. The ground electrode 654 is arranged in a
position at which, when the second transmission device 650 has been
mounted on the first transmission device 630, the ground electrode
654 is capable of capacitive coupling with the ground to which the
communication circuit 631 of the first transmission device 630 is
connected.
The transmission device 610 in which the second transmission device
650 with the above-described configuration is mounted on the first
transmission device 630 has a similar configuration to that of the
transmission device 300 according to the third embodiment.
As in the transmission device 510 according to the fifth
embodiment, the signal electrode 652 in the transmission device 610
according to the present embodiment is arranged on a surface 650a,
where communication takes place, of the second transmission device
650 mounted on the first transmission device 630 so that an
electric field signal can be transmitted at the position where a
magnetic field signal is generated by the first magnetic field
antenna 632. A magnetic field signal and an electric field signal
are therefore transmitted from the same position on the surface
650a of the second transmission device 650. In the present
embodiment, this position on the surface 650a corresponds to the
"communication position". In the present embodiment as well, the
second transmission device 650 may include any display 655 on the
surface 650a to indicate the communication position.
The electronic ticket 620 in the present embodiment includes an IC
chip 621 and a magnetic field antenna 622. The functions of the IC
chip 621 and the magnetic field antenna 622 are similar to those of
the IC chip 521 and the magnetic field antenna 522 included in the
electronic ticket 520 of the fifth embodiment. Hence, a detailed
description thereof is omitted.
In the transmission system 600 according to the present embodiment,
magnetic field communication between the transmission device 610
and the electronic ticket is achieved by the same principle as
described in the fifth embodiment by the user passing the
electronic ticket 620 over the communication position of
transmission device 610.
Like the card holder 540 in the fifth embodiment, the card holder
640 in the present embodiment includes an attachment portion, such
as a belt, allowing the user to attach the card holder 640 to the
wrist, arm, or the like.
The card holder 640 in the present embodiment includes a magnetic
field antenna 641, a matching circuit (resonant circuit) 642, a
first coupling electrode 643, and a second coupling electrode 644.
In the card holder 640, the functions of the magnetic field antenna
641, the matching circuit 642, and the first coupling electrode 643
are similar to the functions of the magnetic field antenna 541, the
matching circuit 542, and the signal electrode 543 of the card
holder 540 in the fifth embodiment. Hence, a detailed description
thereof is omitted.
The card holder 640 in the present embodiment differs from the card
holder 540 in the fifth embodiment by not including the terminal
line and by including the second coupling electrode 644. The second
coupling electrode 644 is coupled to the matching circuit 642. The
second coupling electrode 644 is arranged in the card holder 640 at
a position that comes in contact with the user (human body) when
the user has the card holder 640 wrapped around the wrist or the
like. In other words, the second coupling electrode 644 is in a
state of being electrically coupled to the user when the user has
the card holder 640 wrapped around the wrist or the like. The first
coupling electrode 643 and the second coupling electrode 644 are
arranged in the card holder 640 at a position such that while the
user has the card holder 640 wrapped around the wrist or the like,
the portion of the human body that comes in contact with the first
coupling electrode 643 (such as a fingertip) functions as a
transmission medium for electric field communication with the
transmission device 610, and the portion of the human body that
comes in contact with the second coupling electrode 644 (the entire
body excluding the portion from the wrist where the card holder is
attached towards the distal side) functions as a terminal line.
Here, the principle by which the human body functions as a
transmission medium and a terminal line is described. FIG. 9
schematically illustrates the state in which the card holder 640 is
coupled to a dielectric 700. In FIG. 9, the dielectric 700 is
illustrated schematically as being cylindrical. Furthermore, FIG. 9
illustrates the functional components that transmit and receive
high frequency power collectively as a transceiver unit 645 in the
card holder 640 with the electronic ticket 620 inserted
therein.
As illustrated in FIG. 9, the cylindrical dielectric 700 has a
first bottom (first end) 710a and a second bottom (second end)
710b. The height of the cylindrical dielectric 700 is greater than
the diameter of the bottoms (the first bottom 710a and second
bottom 710b) of the dielectric 700. The height direction of the
cylinder is also referred to as the longitudinal direction.
The card holder 640 couples to the dielectric 700 so that the first
coupling electrode 643 and the second coupling electrode 644 are
side-by-side in the longitudinal direction of the dielectric 700.
Here, it is assumed that the first coupling electrode 643 is
coupled to be closer to the first bottom 710a, and the second
coupling electrode 644 is coupled to be closer to the second bottom
710b.
In the dielectric 700 to which the card holder 640 is coupled, the
region from the position at which the first coupling electrode 643
is coupled towards the first bottom 710a is referred to as a first
region 700a, and the region from the position at which the second
coupling electrode 644 is coupled towards the second bottom 710b is
referred to as a second region 700b. The height of the first region
700a (the length in the longitudinal direction) is referred to as
La, and the height of the second region 700b as Lb. By the user
coupling the first coupling electrode 643 and the second coupling
electrode 644 of the card holder 640 to the dielectric 700 at the
below-described predetermined positions, the first region 700a
functions as a transmission medium, and the second region 700b
functions as a terminal line.
Here, the predetermined positions for the first region 700a to
function as a transmission medium and the second region 700b to
function as a terminal line are described. The card holder 640 is
coupled to a position on the dielectric 700 such that the length Lb
is an electrical length of ((2n+1).times.90).degree.. When the
length Lb is an electrical length of ((2n+1).times.90).degree., a
transmission system capable of electric field communication is
established by the card holder 640, the dielectric 700, and the
transmission device 610 upon the first region 700a coupling with
the schematically illustrated signal electrode 652 of the
transmission device 610, as illustrated in FIG. 10. In this case,
by the principle explained with reference to FIG. 2, a standing
wave is generated with a maximum voltage amplitude and zero current
amplitude at the second bottom 710b of the second region 700b and
zero voltage amplitude and maximum current amplitude at the end of
the second region 700b where the second coupling electrode 644 is
coupled. From the transceiver unit 645, current thus flows towards
the second region 700b of the dielectric 700 through the second
coupling electrode 644, and current flows towards the first region
700a through the first coupling electrode 643. Consequently, the
card holder 640 can communicate with the transmission device 610
using the first region 700a as a transmission medium. In this way,
the second region 700b functions as the terminal line 170
illustrated in FIG. 2.
As explained with reference to FIG. 2, a certain advantage in high
frequency transmission is still obtained when the electrical length
of the terminal line 170 is within a range of .+-.45.degree. of
90.degree., i.e. when the phase of the reflected wave is greater
than 90.degree. and smaller than 270.degree.. Therefore, coupling
at a position such that the length Lb becomes an electrical length
in a range of ((2n+1).times.90.+-.45).degree. is sufficient for the
second region 700b to function as a terminal line.
The card holder 640 is coupled to a position on the dielectric 700
such that the length La is an electrical length of
(2n.times.90).degree.. If the length La were also an electrical
length of ((2n+1).times.90).degree. like the length Lb, then the
first region 700a would function as a terminal line and the second
region 700b would function as a transmission medium upon the second
region 700b coupling with the signal electrode 652 of the
transmission device 610, as illustrated in FIG. 11. In other words,
in this configuration, either the first region 700a or the second
region 700b can function as a terminal line.
However, when the transmission device 100 is coupled to the
dielectric 700 at a position such that the length La of the first
region 700a is an electrical length of (2n.times.90).degree., the
standing wave illustrated in FIG. 2 is not generated at the end on
the side where the first coupling electrode 643 of the first region
700a is coupled. Consequently, the first region 700a does not
function as the terminal line 170, and no virtual ground is formed,
even if the second region 700b couples to the signal electrode 652
of the transmission device 610, as illustrated in FIG. 11. This
prevents the establishment of communication between the card holder
640 and the transmission device 610.
In this way, when the card holder 640 is coupled at a position such
that the length La of the first region 700a is an electrical length
of (2n.times.90).degree. and the length Lb of the second region
700b is an electrical length of (2(n+1).times.90).degree., the
second region 700b of the dielectric 700 functions as a terminal
line, whereas the first region 700a of the dielectric 700 does not
function as a terminal line. Hence, the card holder 640 establishes
communication when the signal electrode 652 of the transmission
device 610 is coupled to the first region 700a but does not
establish communication when the signal electrode 652 is coupled to
the second region 700b.
In this way, by coupling the card holder 640 to a predetermined
position of the dielectric 700, a region allowing establishment of
communication and a region not allowing establishment of
communication upon coupling with the signal electrode 652 can be
formed in the dielectric 700. In other words, the region allowing
establishment of communication in the dielectric 700 can be
restricted in this way. Consequently, the region allowing
establishment of communication can be restricted when the card
holder 640 is coupled at the predetermined position on the
dielectric 700, reducing the likelihood of unintended communication
and facilitating prevention of unintended information leaks. The
card holder 640 in the present embodiment improves safety with
respect to this point.
It suffices for the card holder 640 to be coupled at a position
where the length La of the first region 700a is such that no
standing wave is generated in the first region 700a. It thus
suffices for the card holder 640 to be coupled at a position such
that the length La is an electrical length in a range of
(2n.times.90.+-.45).degree..
FIG. 12 illustrates an example transmission system 600 configured
by coupling the card holder 640 of FIG. 8 to a human body 720,
which is a dielectric. As illustrated in FIG. 12, the first
coupling electrode 643 and the second coupling electrode 644 are
coupled to the human body 720 by the card holder 640 being attached
to the finger, arm, or the like of a human body, for example. At
this time, the first coupling electrode 643 and the second coupling
electrode 644 couple to the human body 720 so as to be side-by-side
in a direction from the torso side towards the distal side of the
arm. For example, the card holder 640 may be formed as a wristband,
an armband, or the like so as to be attachable to the wrist, the
arm, or other body part when the card holder 640 is coupled to the
human body 720.
When the card holder 640 is coupled to the human body 720, the card
holder 640 uses an electric field signal of a predetermined
frequency so that the region from the first coupling electrode 643
coupled on the distal side to the end (for example, the fingertip)
becomes the first region 700a illustrated in FIG. 9, and the region
from the second coupling electrode 644 on the torso side to the
entire arm, torso, and leg becomes the second region 700b
illustrated in FIG. 9. The predetermined frequency may, for
example, be 13.56 MHz. When the frequency of the electric field
signal is 13.56 MHz, then coupling the second coupling electrode
644 to the human body 720, which is a dielectric, on the torso side
near a wrist yields an electrical length of approximately
90.degree. as the length of the second region and an electrical
length of less than 45.degree. as the length of the first region,
supposing that the human body 720 is a typical adult height (such
as 170 cm). Hereinafter, the frequency of the signal used by the
card holder 640 is assumed to be 13.56 MHz. Furthermore, the region
from the first coupling electrode 643 on the distal side to the end
(for example, the fingertip) is referred to as the distal side 720a
of the human body 720, and the region from the second coupling
electrode 644 on the torso side to the entire arm, torso, and leg
is referred to as the torso side 720b of the human body 720.
When a fingertip, for example, of the human body 720 to which the
card holder 640 is attached comes into contact with the
communication position of the transmission device 610, then a
standing wave is generated on the torso side 720b of the human body
720, forming a virtual ground. In other words, the torso side 720b
functions as a terminal line. The distal side 720a functions as a
transmission medium. Electric field communication is thus achieved
through the human body 720, which functions as a transmission
medium, between the transmission device 610 and the card holder 640
with the electronic ticket 620 inserted therein. The transmission
device 610 in the present embodiment may be any of the transmission
devices 100 to 400 in the first through fourth embodiments.
In the present embodiment, the distal side 720a does not function
as a terminal line, and hence communication is not established,
when the torso side 720b of the human body 720 to which the card
holder 640 is attached couples to the signal electrode 652. In
other words, the transmission system 600 according to the present
embodiment allows electric field communication while reducing the
likelihood of unintended communication, thereby facilitating
prevention of unintended information leaks and improving
safety.
In this way, the transmission system 600 according to the present
embodiment allows the user to selectively communicate either by
magnetic field communication or electric field communication. The
user can easily select between magnetic field communication and
electric field communication by inserting the electronic ticket 620
in the card holder 640. Furthermore, the user can use the
electronic ticket 620 capable of magnetic field communication to
perform electric field communication in the transmission system 600
by inserting the electronic ticket 620 in the card holder 640. In
the case of the magnetic field communication system being an
existing system, the transmission system 600 can thus achieve
electric field communication using such an existing asset.
Furthermore, in the transmission system 600 according to the
present embodiment, the transmission device 610 can be configured
by attaching the second transmission device 650 to an existing
first transmission device 630. This allows the transmission device
610 to be configured easily, without the need to change the
configuration of the existing first transmission device 630.
In the sixth embodiment, the case of the first coupling electrode
643 of the card holder 640 being coupled to the terminal side 720a
of the human body 720 and the second coupling electrode 644 being
coupled to the torso side 720b has been described. Electric field
communication is also established in the transmission system 600,
however, when the second coupling electrode 644 is coupled to the
terminal side 720a and the first coupling electrode 643 is coupled
to the torso side 720b. In this case, the above-described functions
of the first coupling electrode 643 and the second coupling
electrode 644 are switched, with the portion on the distal side of
the second coupling electrode 644 functioning as a transmission
medium and the portion on the torso side of the first coupling
electrode 643 functioning as a terminal line.
In the fifth and sixth embodiments, the electric field
communication device that the user uses for electric field
communication has been described as being a card holder into which
an electronic ticket, which is a magnetic field communication
device, can be inserted. The electric field communication device is
not, however, limited to this example. The user may perform
electric field communication using a dedicated electric field
communication device configured to be attachable to a human body,
such as a wristband or armband.
Embodiments of the present disclosure have been described in
detail. A person of ordinary skill in the art, however, could make
modifications or substitutions to the above embodiments without
departing from the scope of the present disclosure. In other words,
the present disclosure is not limited to the above embodiments, and
a variety of modifications and changes are possible. For example,
the functions and the like included in the various components may
be reordered in any logically consistent way. Furthermore,
components may be combined into one or divided.
The matter disclosed in the present disclosure is not intended to
be all-encompassing. That is, the present disclosure does not deny
the existence of subject matter not claimed in the present
disclosure, i.e. the existence of subject matter of a later
divisional application or subject matter to be added by
amendment.
The present disclosure includes examples for the purpose of
illustration but is not to be considered limited by the content of
such examples.
REFERENCE SIGNS LIST
100, 200, 300, 400, 510, 610 Transmission device
110, 210, 310, 410, 511, 631 Communication circuit
120, 522, 541, 622, 641 Magnetic field antenna
130, 230, 330, 430, 513, 542, 642, 651 Matching circuit
140, 240, 340, 440, 514, 543, 652 Signal electrode
150 Electric field communication device
151 Transceiver
152a, 152b Input/output terminal
160 Transmission medium
170, 460, 544 Terminal line
170a, 170b End
220, 320, 420, 512, 632 First magnetic field antenna
250, 350, 450, 515, 653 Second magnetic field antenna
360, 654 Ground electrode
470 Connection terminal
500, 600 Transmission system
520, 620 Electronic ticket
521, 621 IC chip
530 Automatic ticket gate
530a, 650a Surface
531, 655 Display
540, 640 Card holder
630 First transmission device
643 First coupling electrode
644 Second coupling electrode
645 Transceiver unit
650 Second transmission device
700 Dielectric
700a First region
700b Second region
710a First bottom
710b Second bottom
720 Human body
720a Distal side
720b Torso side
* * * * *